Sarah Powell's breast cancer diagnosis, at 29, came as a shock. But four weeks after she finished her treatment, which included chemotherapy and radiotherapy, she was in for another surprise. She was pregnant.

Ms Powell's medical team had advised her to wait two years before trying to conceive, citing the risk of the cancer recurring.

"My husband and I went through IVF before I started chemo to freeze embryos," she said. "We were told so often that chemo would affect my fertility we just got careless. We thought it would never happen. Then it did."

Ms Powell's daughter, Mikayla, was born four years ago and the Melbourne bank worker is expecting her second baby in October.

New research presented at the European Breast Cancer Conference in Vienna this month suggests that young women who are diagnosed with breast cancer and hope to have children can conceive without it increasing their risk of the disease returning. The research, by a team from the Jules Bordet Institute in Brussels, disputes advice that women need to wait two years following breast cancer treatment before trying to conceive.

The chief executive of the Cancer Council NSW, Dr Andrew Penman, is cautiously optimistic about the findings. "There has always been a degree of speculation about whether pregnancy after breast cancer is safe, whether it increases your risk of breast cancer recurring."

Breast cancer is still relatively rare in younger women with about 2 per cent of cases among women aged between 20 and 34, according to the Australian Institute of Health and Welfare.

The research results would spark further study into the causes of breast cancer recurrence, said the director of research investment at the National Breast Cancer Foundation, Alison Butt.

“While this research is still at a preliminary stage, it . . . gives us some intriguing clues as to what may or may not cause breast cancers to reoccur, as it suggests that the increased oestrogen levels that occur during pregnancy might not necessarily trigger a return of the cancer as previously thought."

Ms Powell's friend, Lisa Kidd, whom she met through the online breast and ovarian support group Pink Hope, was also diagnosed young. She was 30 and nursing her nine-month-old son Mitchell when she felt a lump in her breast. Advised to start treatment straight away, she was focused more on survival than her fertility.

She too was told she should wait two years before trying for a baby and her fertility would be compromised. However, she is now expecting her second baby.

"I'd booked myself in for some reproductive assistance but I didn't get to that appointment," the primary school teacher said.

Both women, now 35, carry BRCA gene mutations associated with a higher risk of breast and ovarian cancer. They have undergone bilateral mastectomies and plan to have their ovaries removed after their children are born to reduce the risk of ovarian cancer.

"We hope to have it all done and move on to be healthy mothers who can stick around for a long time," Ms Kidd said.
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